It is well known that vacuum provides an excellent thermal insulator. Vacuum-sealed spaces have been incorporated in a wide variety of structures including cryogenic devices, such as medical probes, and high temperature devices, such as heat exchangers. It is also known to include gas-absorbing material, most commonly a “non-evaporable getter” material, within the vacuum-sealed space in order to achieve a sealed vacuum deeper than the vacuum of the chamber in which the insulating space is evacuated. The getter material, which may comprise metals such as zirconium, titanium, niobium, tantalum, and vanadium, as well as alloys of those metals, may be loosely contained within the vacuum space or, alternatively, coated on the inside of one or more of the surfaces defining the vacuum space.
The presence of the getter material in the vacuum space, whether loosely contained or as a coating, will limit the minimum possible width of the vacuum space. In applications where the width of the vacuum space is small, such as that encountered in many medical devices, space constraints prohibit the use of getter material in the vacuum space. The ability to form a deep vacuum in such applications without the need for getter material is therefore highly desirable.